Roberto Agustin “Robert” Trujillo (born October 23, 1964) is an American musician, best known for his role as the current bassist of heavy metal band Metallica. He was also a member of crossover thrash metal band Suicidal Tendencies, funk metal supergroup Infectious Grooves, and heavy metal band Black Label Society, and has worked with Jerry Cantrell and Ozzy Osbourne. He is currently touring intermittently with experimental metal group Mass Mental.